Orlymanite

Formula: Ca₄Mn₃Si₈O₂₀(OH)₆.2H₂O

Origin of name: for Orlando Lyman, founder of Hawaiian museum

Crystal system: hexagonal

Crystal class: -3 or 3

Twinning: 

Unit cell: 

Colour: dark brown

Diaphaneity: 

Luster: vitreous

Habit: radiating tightly packed rosettes forming spheres 2 to 3 mm across, irregular aggregates

Hardness: 4 to 5

Specific gravity: 2.7 to 2.8

Cleavage: 1; {001} perfect

Tenacity: 

Streak: light brown

Synonyms/varieties:

Comments: related to gyrolite family minerals